Wavelength division multiplexed hardware can operate multiple different formats. However, it may be difficult to determine in advance which kinds of hardware are necessary for different applications. For example, WDM applications may benefit from scalable transponders. These transponders may operate according to multiple formats. They may operate at different wavelengths, and different wavelength spacings.
The present application teaches a special module in which a WDM receiver array with pluggable transmitters is formed. The module enables multiple different transmitter modules to be selectively used and substituted for any others. Any of those may be added or substituted. A single transponder solution may be used for all of the modules.